8661921 has 4 divisors (see below), whose sum is σ = 11549232. Its totient is φ = 5774612.

The previous prime is 8661901. The next prime is 8661941. The reversal of 8661921 is 1291668.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (8661901) and next prime (8661941).

It is a cyclic number.

It is not a de Polignac number, because 8661921 - 2⁵ = 8661889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (8661901) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1443651 + ... + 1443656.

It is an arithmetic number, because the mean of its divisors is an integer number (2887308).

Almost surely, 2^8661921 is an apocalyptic number.

It is an amenable number.

8661921 is a deficient number, since it is larger than the sum of its proper divisors (2887311).

8661921 is a wasteful number, since it uses less digits than its factorization.

8661921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2887310.

The product of its digits is 5184, while the sum is 33.

The square root of 8661921 is about 2943.1141670007. The cubic root of 8661921 is about 205.3705058518.

The spelling of 8661921 in words is "eight million, six hundred sixty-one thousand, nine hundred twenty-one".